Janssen Research & Development announced updated results from the Phase 3 study of Zytiga (abiraterone acetate) plus prednisone demonstrating that it continued to provide statistically significant improvements in disease progression compared to placebo plus prednisone, and longer overall survival in men with metastatic castration-resistant prostate cancer (mCRPC).

Study COU-AA-302 was a Phase 3, randomized, double-blind, multicenter, placebo-controlled international clinical study, which evaluated Zytiga plus prednisone compared to placebo plus prednisone in 1,088 men with mCRPC who had failed androgen deprivation therapy and had not received cytotoxic chemotherapy. The co-primary endpoints of the study are radiographic progression-free survival (rPFS) and overall survival (OS).

The analysis showed a statistically significant 47% reduction in risk of disease progression, which was measured as rPFS in the Zytiga plus prednisone arm compared to the placebo plus prednisone arm. The median rPFS was 16.5 months in the Zytiga arm vs. 8.3 months in the control arm [hazard ratio (HR) 0.53; 95% confidence interval (CI): 0.45 to 0.62; P<0.0001]. At the time of the interim analysis, the co-primary endpoint of overall survival was not met.

Zytiga is approved in combination with prednisone for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC).

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